title: Preprocedural clinical parameters determining perimitral conduction time during mitral isthmus line ablation.
abstract: BACKGROUND
  Achievement of complete conduction block across left mitral isthmus (MI) is challenging. Anticipation of perimitral conduction time (PMCT) associated with MI block may expedite this procedure. We evaluated the relationship between the preprocedural variables and the quantum of PMCT in patients with bidirectionally blocked MI.
  
  
  RESULTS
  We reviewed clinical and echocardiographic parameters in 290 consecutive patients with confirmed bidirectional MI block during atrial fibrillation (AF) ablation. PMCT was defined as the temporal delay to the latest of the double potentials on the line of block while pacing posteroseptal to it in the left atrium (LA). LA size and type of AF significantly influenced PMCT in multivariate analysis. A cumulative score based on LA size (0≦45 mm; 1>45 mm) and type of AF (0: paroxysmal; 1=nonparoxysmal) ranged from 0 to 2. PMCT was directly correlated to the cumulative score (0: 169 ms; n=78; 95% confidential interval, 156 to 181); 1: 187 ms; n=103; 95% confidential interval, 178 to 196; 2: 209 ms; n=109; 95% confidential interval, 200 to 217). In 61 patients who underwent AF ablation twice, the difference between 2 PMCT values was <30 ms in 75% patients. Another consecutive 143 patients with and without MI block after at least 15 minutes of radiofrequency application were analyzed. Perimitral conduction delay <130 ms ruled out bidirectional MI block. Perimitral conduction delay >173 ms predicted bidirectional block with an accuracy of 86%.
  
  
  CONCLUSIONS
  LA size and AF type significantly influence PMCT in patients undergoing successful MI ablation. These parameters can be used to predict the time value associated with MI block, preprocedurally.
authors.affiliation: Hôpital Cardiologique du Haut-Lévêque, Université Victor Segalen Bordeaux II, France. mshinsuke@k3.dion.ne.jp
authors.forename: Shinsuke
authors.initials: S
authors.lastname: Miyazaki
authors.forename: Ashok J
authors.initials: AJ
authors.lastname: Shah
authors.forename: Xingpeng
authors.initials: X
authors.lastname: Liu
authors.forename: Amir S
authors.initials: AS
authors.lastname: Jadidi
authors.forename: Isabelle
authors.initials: I
authors.lastname: Nault
authors.forename: Matthew
authors.initials: M
authors.lastname: Wright
authors.forename: Andrei
authors.initials: A
authors.lastname: Forclaz
authors.forename: Nick
authors.initials: N
authors.lastname: Linton
authors.forename: Olivier
authors.initials: O
authors.lastname: Xhaët
authors.forename: Lena
authors.initials: L
authors.lastname: Rivard
authors.forename: Nicolas
authors.initials: N
authors.lastname: Derval
authors.forename: Sébastien
authors.initials: S
authors.lastname: Knecht
authors.forename: Frédéric
authors.initials: F
authors.lastname: Sacher
authors.forename: Mélèze
authors.initials: M
authors.lastname: Hocini
authors.forename: Pierre
authors.initials: P
authors.lastname: Jaïs
authors.forename: Michel
authors.initials: M
authors.lastname: Haïssaguerre
mesh_terms: D020517:Atrial Appendage / Q000503:physiopathology* / Q000601:surgery; D018780:Body Surface Potential Mapping / Q000379:methods*; D017115:Catheter Ablation / Q000379:methods*; D054326:Coronary Sinus / Q000503:physiopathology*; D005260:Female; D005500:Follow-Up Studies; D006329:Heart Conduction System / Q000503:physiopathology* / Q000601:surgery; D006801:Humans; D008297:Male; D008875:Middle Aged; D011300:Preoperative Care / Q000379:methods*; D012189:Retrospective Studies; D016896:Treatment Outcome